An example of a conventional DC-DC converter is a so-called synchronous buck converter. It has minimal components, and therefore is widely used in voltage regulator applications. In an example conventional application, the input voltage to the buck converter is typically 12VDC. An output voltage produced by the buck converter may be 5.0VDC, 3.3 VDC, or even lower.
A typical configuration of a conventional voltage converter includes one or more power converter phases. Each power converter phase can include an inductor, a high side switch (a.k.a., a control switch) and a low side switch (a.k.a., a synchronous switch).
In general, during operation, a control circuitry associated with a conventional voltage converter repeatedly pulses the high side switch ON to convey power from a power source through the one or more inductors in the phases to a dynamic load. The control circuitry repeatedly pulses the low side switch ON (in between switching the high side switch ON) to provide a low impedance path from a node of the inductor to ground. Thus, the energy stored in the inductor increases during a time when the high side switch is ON and decreases during a time when the low side switch is ON. During switching operation, the inductor transfers energy from the input to the output of the converter.
In certain power supply applications, it is useful to know how much current is delivered to a respective load by each of one or more phases in the power supply. For example, the average current value can be used as an input to a control loop.
To measure current, one conventional application includes disposing a resistor in a respective phase. The resistor is disposed in series with an inductor of the respective phase. Via measurements of the differential voltage across the resistor, it is possible to determine how much current is delivered by the phase to a respective load.
In accordance with another conventional technique, such as a so-called DCR (Direct Current Resistance) method, a series circuit including a resistor and a capacitor can be disposed in parallel with the inductor of a respective power supply phase. In theory, the RC time constant will produce a measurable capacitor voltage that matches the inductor current. Thus, based on the voltage across the resistor in the DCR sensing circuit, it is possible to determine how much current is delivered by the phase to a respective load.